Wide angle optical retarder

Abstract

In an acrylonitrile based retarder, relatively uniform performance is obtained as the angle of incidence varies over a wide range. A toughening material may be blended with an acrylonitrile based polymer to facilitate processing of a retarder and improve mechanical properties of the retarder without compromising the optical performance. A rubber-modified acrylonitrile based retarder which provides relatively uniform wide angle can be fabricated using conventional processing techniques. Such retarders are particularly suited for a number of specific applications which use relatively wide ranges of incidence angles.

What is claimed is:  
     
       1. An anti-reflective (AR) optical element operable when disposed proximate to a partially reflective surface to substantially reduce reflection of visible light from the surface over a relatively wide range of incidence angles, the AR optical element comprising: 
       an absorptive polarizer having an incident light side and a reflective surface side; and  
       an acrylonitrile-based optical retarder disposed adjacent the reflective surface side of the absorptive polarizer, wherein a retardation magnitude for light at of a wavelength of interest incident on the retarder at an angle normal to a surface of the retarder is within 15% of a retardation magnitude for light of the wavelength of interest incident on the retarder at an angle of incidence of at least about 30°, measured from normal incidence.  
     
     
       2. An anti-reflective (AR) optical element as recited in claim  1 , wherein the acrylonitrile-based optical retarder comprises a blend of an acrylonitrile based polymer and an elastomeric copolymer. 
     
     
       3. An anti-reflective (AR) optical element as recited in claim  1 , further comprising a substrate having a first and second side, the first side of the substrate being affixed to the incident light side of the absorptive polarizer, wherein an antireflective coating is coated on the second side of the substrate. 
     
     
       4. An anti-reflective (AR) optical element as recited in claim  1 , wherein the AR optical element is adapted to reduce glare reflections from a screen of a computer monitor. 
     
     
       5. An optical element operable over a relatively wide range of incidence angles, comprising: 
       an absorptive polarizer; and  
       an acrylonitrile-based optical retarder disposed adjacent a side of the absorptive polarizer, wherein a retardation magnitude for light at of a wavelength of interest incident on the retarder at an angle normal to a surface of the retarder is within 15% of a retardation magnitude for light of the wavelength of interest incident on the retarder at an angle of incidence of at least about 30°, measured from normal incidence.